package com.shycloud.mido.gateway.util;

import java.io.ByteArrayOutputStream;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.Cipher;
import org.apache.commons.codec.binary.Base64;
import org.springframework.http.server.reactive.ServerHttpRequest;

/**
 * @author Xiaoxing Yu
 * @date 2020/8/20
 **/
public class RSAUtil {

	public static final String privateKey =
			"MIICdwIBADANBgkqhkiG9w0BAQEFAASCAmEwggJdAgEAAoGBAOErQDraPhHm0aZF" +
					"uANV7GpL1Fm4DBx477yQCSUAgtjfQZZG6uMGFt990En8P6gLSu6W8aNMO0J0ShV7" +
					"g4kqrhSVBXmqDFLkUZAqCLnaMD3MObSjXI7GcSAceIWsy/fqA7VIkYhv9Ze3RwB5" +
					"YmQMFzZf/ZgTbrX7R4a5l0Y9Qaz9AgMBAAECgYEAl9NwBb7up2d56aGNCELBnJLw" +
					"5mYhVHl/PSfp4pdLoyw2rzu2WcnbVmshLSH3Ujn7FpGU8UUPmCmNYprcAHtU0Kw5" +
					"xGady+M7feJkrvivpVxG6K7P8hBO+C68ZL0x9ZwgovsPi0Kg2qitH9EnWj7LzLkC" +
					"wXsnmV3c9aIY1hMU3IECQQDxtFCBGVubojx42cKU9GDkh8MSH4eiOown8KS6a3J1" +
					"5Gdm5t4/9zQsVQQpE5t+uQJfhgF9szffCGhBNr4WCePtAkEA7nySNgRvaqja852/" +
					"GoLu5ioE0FhymmwsaOx5aei/rKaLiL0P4TS7nPmPaYNI2Mh8wmEG22IW5wReHpGW" +
					"Xr7rUQJBALObxmborQZN3JoBV3LQ1l978x04iNWopBXZ4M8WoQuyGpSA4o6t5/s5" +
					"gcn0ZAwa9wR81AbQcqgt2yr6vu4pk1ECQC1kdIfnjDVm8lXQPqGTLlmMweHOE/Ik" +
					"iMdnyyxHasQ35vMd2TnqSZN1RMC2hlUMxAJTaXS0VNufzzJOT6q0+CECQFiJPn0o" +
					"D8s+l/sGpgXM28iXqdT2/lH7Xysswj5QmdVZBd8dVdWk/XxQQ0QStq1kfzcGcL9D" +
					"oAOoaHU8mRFRSrw=";

	public static final String publicKey =
			"MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDhK0A62j4R5tGmRbgDVexqS9RZ" +
					"uAwceO+8kAklAILY30GWRurjBhbffdBJ/D+oC0rulvGjTDtCdEoVe4OJKq4UlQV5" +
					"qgxS5FGQKgi52jA9zDm0o1yOxnEgHHiFrMv36gO1SJGIb/WXt0cAeWJkDBc2X/2Y" +
					"E261+0eGuZdGPUGs/QIDAQAB";

	/**
	 * RSA最大加密明文大小
	 */
	private static final int MAX_ENCRYPT_BLOCK = 117;

	/**
	 * RSA最大解密密文大小
	 */
	private static final int MAX_DECRYPT_BLOCK = 128;

	/**
	 * 获取密钥对
	 *
	 * @return 密钥对
	 */
	public static KeyPair getKeyPair() throws Exception {
		KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");
		generator.initialize(1024);
		return generator.generateKeyPair();
	}

	/**
	 * 获取私钥
	 *
	 * @param privateKey 私钥字符串
	 * @return
	 */
	public static PrivateKey getPrivateKey(String privateKey) throws Exception {
		KeyFactory keyFactory = KeyFactory.getInstance("RSA");
		byte[] decodedKey = Base64.decodeBase64(privateKey.getBytes());
		PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(decodedKey);
		return keyFactory.generatePrivate(keySpec);
	}

	/**
	 * 获取公钥
	 *
	 * @param publicKey 公钥字符串
	 * @return
	 */
	public static PublicKey getPublicKey(String publicKey) throws Exception {
		KeyFactory keyFactory = KeyFactory.getInstance("RSA");
		byte[] decodedKey = Base64.decodeBase64(publicKey.getBytes());
		X509EncodedKeySpec keySpec = new X509EncodedKeySpec(decodedKey);
		return keyFactory.generatePublic(keySpec);
	}

	/**
	 * RSA加密
	 *
	 * @param data 待加密数据
	 * @param publicKey 公钥
	 * @return
	 */
	public static String encrypt(String data, PublicKey publicKey) throws Exception {
		Cipher cipher = Cipher.getInstance("RSA");
		cipher.init(Cipher.ENCRYPT_MODE, publicKey);
		int inputLen = data.getBytes().length;
		ByteArrayOutputStream out = new ByteArrayOutputStream();
		int offset = 0;
		byte[] cache;
		int i = 0;
		// 对数据分段加密
		while (inputLen - offset > 0) {
			if (inputLen - offset > MAX_ENCRYPT_BLOCK) {
				cache = cipher.doFinal(data.getBytes(), offset, MAX_ENCRYPT_BLOCK);
			} else {
				cache = cipher.doFinal(data.getBytes(), offset, inputLen - offset);
			}
			out.write(cache, 0, cache.length);
			i++;
			offset = i * MAX_ENCRYPT_BLOCK;
		}
		byte[] encryptedData = out.toByteArray();
		out.close();
		// 获取加密内容使用base64进行编码,并以UTF-8为标准转化成字符串
		// 加密后的字符串
		return new String(Base64.encodeBase64String(encryptedData));
	}

	/**
	 * RSA解密
	 *
	 * @param data 待解密数据
	 * @param privateKey 私钥
	 * @return
	 */
	public static String decrypt(String data, PrivateKey privateKey) throws Exception {
		Cipher cipher = Cipher.getInstance("RSA");
		cipher.init(Cipher.DECRYPT_MODE, privateKey);
		byte[] dataBytes = Base64.decodeBase64(data);
		int inputLen = dataBytes.length;
		ByteArrayOutputStream out = new ByteArrayOutputStream();
		int offset = 0;
		byte[] cache;
		int i = 0;
		// 对数据分段解密
		while (inputLen - offset > 0) {
			if (inputLen - offset > MAX_DECRYPT_BLOCK) {
				cache = cipher.doFinal(dataBytes, offset, MAX_DECRYPT_BLOCK);
			} else {
				cache = cipher.doFinal(dataBytes, offset, inputLen - offset);
			}
			out.write(cache, 0, cache.length);
			i++;
			offset = i * MAX_DECRYPT_BLOCK;
		}
		byte[] decryptedData = out.toByteArray();
		out.close();
		// 解密后的内容
		return new String(decryptedData, "UTF-8");
	}

	/**
	 * 签名
	 *
	 * @param data 待签名数据
	 * @param privateKey 私钥
	 * @return 签名
	 */
	public static String sign(String data, PrivateKey privateKey) throws Exception {
		byte[] keyBytes = privateKey.getEncoded();
		PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
		KeyFactory keyFactory = KeyFactory.getInstance("RSA");
		PrivateKey key = keyFactory.generatePrivate(keySpec);
		Signature signature = Signature.getInstance("MD5withRSA");
		signature.initSign(key);
		signature.update(data.getBytes());
		return new String(Base64.encodeBase64(signature.sign()));
	}

	/**
	 * 验签
	 *
	 * @param srcData 原始字符串
	 * @param publicKey 公钥
	 * @param sign 签名
	 * @return 是否验签通过
	 */
	public static boolean verify(String srcData, PublicKey publicKey, String sign) throws Exception {
		byte[] keyBytes = publicKey.getEncoded();
		X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
		KeyFactory keyFactory = KeyFactory.getInstance("RSA");
		PublicKey key = keyFactory.generatePublic(keySpec);
		Signature signature = Signature.getInstance("MD5withRSA");
		signature.initVerify(key);
		signature.update(srcData.getBytes());
		return signature.verify(Base64.decodeBase64(sign.getBytes()));
	}

	public static boolean verifySign(ServerHttpRequest request) {



		return true;
	}

	public static void main(String[] args) {
		try {
			// 生成密钥对
			KeyPair keyPair = getKeyPair();
			String privateKey = new String(Base64.encodeBase64(keyPair.getPrivate().getEncoded()));
			String publicKey = new String(Base64.encodeBase64(keyPair.getPublic().getEncoded()));
			System.out.println("私钥:" + privateKey);
			System.out.println("公钥:" + publicKey);
			// RSA加密
			String data = "待加密的文字内容";
			String encryptData = encrypt(data, getPublicKey(publicKey));
			System.out.println("加密后内容:" + encryptData);
			// RSA解密
			String decryptData = decrypt(encryptData, getPrivateKey(privateKey));
			System.out.println("解密后内容:" + decryptData);

			// RSA签名
			String sign = sign(data, getPrivateKey(privateKey));
			// RSA验签
			boolean result = verify(data, getPublicKey(publicKey), sign);
			System.out.print("验签结果:" + result);
		} catch (Exception e) {
			e.printStackTrace();
			System.out.print("加解密异常");
		}
	}

}
